Blind bolt installation tool with preloaded torque-responsive driving mechanism



United States Patent Oce ns BLIND BQLT INSTALLATION TGL WITH PRELOADED TRQUE-RESPONSVE DRIVING MECHANISM Ben C. Keasler, San Pedro, Calif., assigner to Lok-Fast, Inc., Torrance, Calif., a corporation of California Filed June 22, 1962, Ser. No. 204,479 10 Claims. (Cl. 81-55) This invention relates to a power-operated nut-holding Wrench for driving a blind bo-lt into la nut, of the general class exemplified by the wrench disclosed in a patent of Joseph La "Ilorre No. 2,789,597, granted April 23, 1957.

The operation of blind bolt driving wrenches in common use during the past ten years has always required the application of considerable forward pressure against the driving gun to maintain the screw-rotating wrench tip and the nut-holding socket coupled to the respective parts of the blind bolt while rotational torque is applied to the screw `and holding torque is applied to the nut. The amount of axial pressure which thus must be applied by the workman in order to set the bolt, in some of the larger sizes, is of such a magnitude as to make it impracticable to utilize the conventional power-driven tool and it is customary, with those sizes, for the workman to do the operation by hand, using one wrench for holding the nut and yanother wrench for turning the screw. This operation is quite time-consuming. The use of the motor driven tool, on the other hand, is tiring because of the necessity lfor the Aworkman to lean his Weight against the tool during the driving operation.

With the yforegoing in mind, the principal object of this invention is to provide a motor-driven blind bolt driving tool embodying torque-energized mechanism for automatically applying an axial thrust against the screwwrenching tip of the tool, neutralizing the normal resistance of the wrenching tip to the axial movement of the 'screw in entering the nut.

Other objects and advantages will become apparent in the lensuing specification and appended drawing in which:

yFIG. 1 is an axial sectional view of a blind bolt wrenching tool embodying my invention, with portions of the screw-wrenching mechanism shown in elevation and at a starting point in a blind bolt-setting operation;

FIG. 2 is an axial sectional view of the same parts, moved to their relative positions at the end of ya normal driving operation;

FIG. 3 is a cross-sectional View taken on the line 3 3 of FIG. 1;

FIG. 4 is a cross-sectional view on the line fi-4 of FIG. 1;

FIG. 5 is a cross-sectional View taken on the line S-5 of FIG. 1;

FIG. 6 is a view, partially in axial section and partially in elevation, of a right-angle driver embodying a modied form of the invention;

FIG. 7 is a side View of the wrenching tip assembly, viewed at right angles .to the line of sight in FIG. 6;

FIG. 8 is a cross-sectional view taken on the line 8-8 of FIG. 6; and

FIG. 9 is Ian end View of the driver of FIG. 6.

General .Description` Referring now to the drawings in detail, and in particular to FIGS. 1-4, I have shown therein, as an example of one dorm in which my invention may be embodied, a blind bolt driving tool of an in-line assembly type, embodying, in general, a housing barrel A attached to and projecting forwardly from a gun or motor, fragmentarily indicated at B; `a nut-holding tip C mounted to the forward end of barrel A and projecting forwardly therefrom; a

torque-responsive wrenching drive transmitting assembly D adapted to receive rotary drive from the drive shaft of the gun B or motor lthrough a dog clutch unit E; and a wrenching tip F detachably secured to the forward end of the drive unit D. The tool is shown in driving rela- Icion to a blind bolt G projecting through adjacent sheets of work H to be secured together.

rPhe tool may utilize any conventional driving gun (a power nnit embodying a motor, e.g. an air motor or other type of motor) encased in a housing to the forward end of which the barrel A is attached. Such housing may embody a suitable pistol grip or other means for holding and manipulating the tool, customarily provided las illustrated in the aforesaid La Torre Patent No. 2,789,597. The motor has a drive shaft projecting forwardly through the housing and terminating in a driving endwhich is shown herein as an externally threaded spindle 101.

Rotation is clockwise as viewed by the operator holding the tool and facing the work. Tlr's direction is indicated by the arrow '11 in FIG. 1. 'Ihe blind bolt G embodies a screw v12 having a left-hand thread land embodying iiats for other driving means on a break-off stem 13 which is twisted loose or broken olf from the screw 12 by increase in drivin-g load when the bolt is fiully set; a nut :14 threaded onto the screw 12; and la fastener collar 15 (or a conical head on screw 12 to expand nut `1d). The collar 15 is expanded to form a head at the blind end of the bolt by expansion overa conical mandrel at the forward end of the nut 14 as the screw 13 is drawn rearwardly into the nut, the collar 15 being driven by the head of the screw v12. The wrenching tip F is coupled to the stem 13 by suitable wrenching faces of a socket 51 (eg. flat faces as shown, or grooves) engaging the non-cylindrical wrenching faces of the stem 13, the rounded faces of the Lsocket being out of engagement with the thread segments of the stem. The nut 14 is held stationary by a suitable wrenching connection between the holding tip C and the nut. As the screw is drawn rearwardly, the driving tip F is correspondingly urged rearwardly by the stem 13, and this movement is facilitated by the torque-responsive action of the drive unit D, until it is retracted to the position shown in FIG. 2, at which point the resistance to the driving of the collar '15 or the conical head of screw 12 into nut 14 will sharply increase by abutting engagement of the collar 15 against the work H and the development of compression in the collar. Consequently the stern 13 will be twisted or broken off at a predetermined point, completing the operation, and the gun can then be withdrawn.

Detailed Description Barrel A comprises a cylindrical body portion 20 having at its rear end a suitable coupli-ng portion 21 (eg. threaded or other attaching means) for coupling connection to the forward end of the housing of gun B, and having at its forward end a reduced throat 22 terminating in an internal thread 23 to receive and mount the holding tip C. An `annular bearing shoulder -24 is provided bet-ween throat 22 and the major internal wall of body 2d.

Holding tip C comprises a body in the form of a cylindrical sleeve 25 having =at its rear end `an externally threaded nipple 26 for coupling it to the thread 23; having, adjacent said nipple 26, a suitable integral wrenching collar 27 -with wrenching Ilats 28 (F-IG. 4) for manipulating it into and attaching it to, also for detaching it from the barrel A; and having vat its forward end an angled nose 29 provided with suitable wrenching jaws 30 engageable in drive recesses or protrusions of any suitable type in the rear end of the nut 14, for establishing :a holding connection therewith. A left hand thread in throat 22 and on the nipple 26 will provide for maintaining a tight Icoupling connection between the parts C and A under the torque reaction load imposed on the holding tip C by the nut 14.

Drive transmission zmt D comprises a. cylindrical socket 3:1 which may, as in the form shown in FIG. 1, be of cup shape including a closed rear end portion 32 terminating in a diametrically extending integral clutch jaw 33 for a clutching connection to the clutch device E, `and terminating in an axially disposed pilot pin 34. Rotatably mounted in a cylindrical bore within the socket 31, and projecting forwardly through the open end thereof, is a driven shaft 35 which has a reduced forward end portion 36 terminating in a cylindrical tang 40 projecting into the rear end portion of wrenching tip F. A drive pin 37 (F-IG. 3) projects diarnetrically through the driven shaft `35, is securely mounted in a diametral .bore therein, and has projecting end portions engaged in helical slots 3S in the driving socket 31. A light coil spring 39 is interposed under compression between the rear end of driven shaft 35 and the bottom of socket 311 defined by end member 32. Spring 39 normally projects the driven shaft 35 to a forward position shown in FIG. 1, but yields to permit the retraction of the driven shaft 35 to the retracted position shown in FIG. 2. The direction of helical inclination of slots 38 is so related to the direction of drive rotation 11 as to develop, by camming action against the projecting ends of pin 37, a rearward pull against the driven shaft 35.

Clutch E comprises a cylindrical body 45 having an internally threaded socket for coupling it to the threaded spindle 10 of the gun drive shaft. Forwardly of the socket, it has a head 46 provided with a central bore to receive the pilot 34 of drive socket 31. Head 46 has a pair of integral clutch jaws 47 of approximately 90 degree quadrant form, in diametrically opposed relation, projecting forwardly therefrom and embracing the diametral clutch jaw 33 of socket 31 with a rotary lost-motion driving connection which accommodates indexing of the driving tip F into wrenching position in relation to the holding tip C when the gun is initially applied to the bolt.

Driving T ip F comprises a cylindrical body t) journalled for rotation in the bore of the holding tip C, having a wrenching socket 51 broached therein along its longitudinal axis, to tit the cross sectional contour of stem 13, receiving the same and providing driving connection therewith. In its rear end, the body 5i) has a counterbore 52 (FIG. 2) receiving the coupling tang 40 of drive unit D and secured thereto by a fastener pin 53 driven through registering bores in the coupled parts. The rear end of the broached socket 51 is normally blocked by an ejector plug 54 (FIG. 2) which, as indicated in FIGS. l and 2, may be slidable in the counterbore 52. Plug 54 has a stem 55, and is yieldingly supported by a coil spring 56 interposed under compression between the plug 55 and the forward end of coupling tang 40 and encircling the stem 55.

In normal operations of the tool, the wrenching socket 51, open and unobstructed in its rear portion, offers no opposition to rearward sliding movement of the stem 13 in the socket except for the torque-energized cramping grip of the wrenching faces of the socket 51 against the at faces of stem 13. The axial thrust transmitted from the stem 13 to the wrenching tip F through such cramping grip will be suiiicient, when added to the camming action of drive pin 37 and slots 38, to cause the wrenching tip F and driven shaft 35 to retract.

Where a screw of abnormal length, such that its rear end Iwill engage and retract the plug 54 when the tool is applied to nut 14, is being driven, the rearward thrust of the stem 13 against the plug 54, transmitted to the driven shaft 35, will retract it against the compression of spring 39, the camming action between the drive pin 37 and the helical slots 38 being operative to assist such retracting movement of the shaft 35 into the socket 31 by neutralizing resistance thereto. As a still further alternative, it is possible to utilize an unyielding bottom at the rear end of socket 51 (as by extending tang 40 down to the position of plug 54 and eliminating the spring 56 and plug 54 so as to provide, in effect, an integral bottom for the socket). In the operation of the tool in this instance, the retracting movement of stem 13 will be positively transmitted to the wrenching tip F through the bottom of its socket, but the reactive thrust against the tool in the hands of the workman will be balanced out by the camming action between drive pin 37 and helical slots 38.

Modified form-FIGS. 6-9.-Referring now to FIGS. 6-9, there are shown therein a number of modified features that may be embodied in the invention. Principally, the modification arises in the adaptation of the invention to an angle driver instead of the in-line type shown in FIGS. l-5. In this arrangement the drive comes through gears 6i) extending at right angles to the driving axis of the tool, from the motor to the terminal drive shaft element having the threaded drive spindle 10 thereon. Since this type of tool is customarily utilized in confined spaces where the axial depth of the tool along the axis of its driving tip is held to a minimum, the lost-motion clutch unit E is eliminated and the drive socket 31 is directly coupled to the threaded drive spindle 10 at its rear end. In lieu of the lost motion clutch unit E, there is provided in the drive socket 31 a pair of circumferentially extending slots 62 communicating with the forward ends of the helical camming slots 38. The driving pin 37 of wrenching tip F is oscillatable in the circumferential slots 62 in the initial stage of application of the tool to the blind bolt, to provide the lost motion self-indexing action of the clutch unit E, and the rearwardly extending slots 3S perform the function of slots 38 of FIG. l. The somewhat moditied form of nut-holding means (a non-cylindrical socket 30') which in its specific aspect forms no part of the present invention, is disclosed in FIG. 6 as an alternative to the holding jaws 30 of FIG. 1. It may have a threaded connection 26 with barrel 20'. The coupling ferrule 27 in this arrangement is shown as an integral part of cover plate 63 of the gear case 64 which corresponds broadly to the gun housing (referred to but not disclosed) of FIGS. 1 and 2. The barrel portion 20' is bored to receive the entire torque-responsive drive unit D of the modification, and is directly coupled to the gear case 64 as shown, through a threaded collar at its rear end. In other respects, the invention of FIG. 6 embodies the features of the apparatus shown in FIGS. 1-4 except as stated hereinafter.

Operation The improvement in operation of my tool over the conventional tool will be better understood by first considering more in detail the operation of the conventional tool. In a tool, such as that shown in the La Torre patent referred to above, wherein the rotating wrenching tip and the fixed holding tip remain in axially-fixed relation while the stem of the screw is drawn axially into the driving socket of the holding tip, retracting a spring-loaded ejector pin in doing so, the torque load transmitted between the driving faces of the wrenching socket and the corresponding faces of the screw stem, causes these faces to frictionally grip one another, creating a drag between the stem and the wrenching socket which gradually increases with increasing torque as the collar 15 is pushed further onto the angled end of nut 14, and since the screw is being positively driven through the nut by the wrenching action, this drag transmits a corresponding backward axial thrust from the screw stem to the wrenching tip F tending to uncouple the tool 29 from the nut 14, thus allowing assembly G to rotate with driver F, and damaging the driving end of nut 14. The backward thrust must be overcome by the operator as he leans forwardly against the tool, in order to prevent the tool releasing itself from the nut 14. In addition, to this drag-induced thrust, the operator must overcome the spring load on the ejector pin which is being retracted by the rearward movement of the screw stem. As previously stated, the aggregate axial counter-thrust that is developed in the conventional tool during a bolt driving operation is of such magnitude that it becomes impractical for the average workman to drive some of the larger sizes of blind bolts, using the conventional tool.

In the operation of my improved tool, the camming angle of slots 38 (as subtended from the driving axis of the tool-coaxial with tips C and F) is such as to develop a camming eiect suicient to equal the counter-thrust developed in the conventional tool, and to make it unnecessary for the workman to exert a forward thrust in excess of the relatively mild forward thrust required for maintaining the holding jaws 30 of the holding tip C socketed in the nut recess or otherwise coupled to the head of nut 14. I iind that a camming angle in the range between and 30 may be utilized.

In normal operation of the tool, as the screw 12 is threaded into the nut 14, its axial movement will be matched by a corresponding retracting movement of the wrenching tip F, transmitted to it from screw 12. This will occur regardless of whether the stem 13 engages an integral bottom of socket 51, transmits movement through pin 54 and spring 56, or transmits axial movement through frictional engagement against the side walls of socket 51 under the torque transmitted between the wrenching tip F and the stem 13.

I iind that the tool can be operated as readily on the largest sizes of blind bolts as on the smaller sizes for which the conventional tool is most satisfactorily adaptable. Also, it may be noted that by selecting different sizes of holding tip C and wrenching tip F, and by utilizing the detachable couplings of these tips of the driving unit D and the barrel A respectively, it becomes possible to use the same gun for the various sizes of bolts.

Where the spring-loaded plug 54 is incorporated in the tool, it can under some circumstances be utilized as an ejector device. For example, if the stem 13 has a length suiiicient to displace the plug 54 rearwardly in the starting position of FIG. l, the application of the tool into coupling engagement with the blind bolt G will result in the plug 54 being retracted against the compression of spring 56. In this instance, the angle of inclination of slots 38 may be suiiicient to absorb the load of spring 56 as Well as the normal resistance to retraction of driving shaft 35. As torque is applied following the coupling connection of the tool with the bolt G, the torqueinduced drag between wrenching tip F and stem 13 normally is such as to hold the parts in the relative positions attained by the coupling of the tool to the bolt, with the plug 54 remaining in its original position and the wrenching tip F being retracted with the assistance of the torque reactive action in driving unit D, in step with the movement of screw 12 into the nut.

Where ejector plug 54 is retracted by a long screw, it would be held retracted up to the point of twist-oil:` of stern 13, thus releasing the part and, as the tool is withdrawn from the work, the plug 54 would become operative to eject the severed stem 13 from the forward end of the tool, assisted by the bodily forward movement of shaft 3S under the propulsive effect of spring 39. In the preferred form of the invention shown herein, the camming slots 38 have an angle such that the torque reaction between the pin 37 and slots 38 just neutralizes the resistance to retraction of the shaft 35 into the socket 31 (developed in the torque-loaded drive-transmitting coupling between the drive parts 31 and 35) in addition to overcoming the load of spring 39. Thus the shaft 35, while being driven at full torque, is free to retract in unison with the axial movement of screw 13, oifering no resistance to such axial movement. By thus balancing the torque-energized axial pull of socket 31 on shaft 35 against the spring load and the torque-loaded resistance to retraction of shaft 35, it is possible lfor the drive unit D to operate in this manner without utilizing an end-thrust bearing at its forward end to restrain it from forward creeping during a driving operation. Annular bearing shoulder IZ4 limits any possible forward drift of socket 31.

I claim:

1. In a tool for setting a bolt-type fastener comprising respective nut and screw elements having wrenching surfaces at the same end of the fastener, in combination: inner and outer wrenching members, one telescoped within the other; means for holding one of said members against rotation; and means for transmitting rotation to the other member, said last means comprising parts relatively shiftable axially and having limited rotative movement with respect to one another, one of said parts transmitting drive to said other member and the other of said parts receiving drive from a motor, and torque-reactive means comprising interengaging surfaces of said parts, at least one of which has an angular inclination with reference to the driving axis of the tool, thereby coupling said parts in a manner to substantially eliminate resistance to retraction of said one part when transmitting torque, whereby said one part may retract in unison with the axial movement of one of said fastener elements with respect to the other as the fastener is closed against parts to be fastened.

2. I-n a tool for setting a bolt-type fastener comprising respective nut and screw elements having wrenching surfaces at the same end of the fastener, in combination: inner and outer wrenching members, one telescoped within the other; means for holding one of said members against rotation; and means for transmitting rotation to the other member, said last means comprising a tubular part and a shaft part socketed in said tubular part for limited rotary and axial movements therein, a helical camming groove in said tubular part, a drive projection extending radially from said shaft part into said groove, a rotary drive connection between one of"said parts and said other member; and means for transmitting rotary drive to the other part, said camming groove being pitched so as to resolve the `drive torque into an axial component balancing out the resistance of the torque-loaded coupling connection between said parts to the axial drawing of said parts together, whereby one of said parts may retract in unison with the axial movement of one of said fastener elements as the fastener is closed against interposed work parts, without resisting such axial movement.

3. In a tool for setting a bolt-type fastener comprising respective nut and screw elements having wrenching surfaces at the same end of the fastener, in combination: inner and outer wrenching members, one telescoped within the other; means for holding one of said members against rotation; and means for transmitting rotation to the other member, said last means comprising a tubular part and a shaft part sooketed in said tubular part for limited rotary and axial movements therein, a helical camming groove in said tubular part, a drive projection extending radially from said shaft part into said groove, means spring-loading said parts for relative axial movement in which said projection assumes one limit position of helical movement in said slot, and a rotary drive connection between one of said parts and said other member; and means for transmitting rotary drive to the other part, said camming groove being pitched so as to resolve the drive torque into an axial component balancing out the resistance of the torque-loaded coupling connection between said parts to the axial drawing of said parts together, whereby oneof said parts may retract in unison with the axial movement of one of said fastener elements as the fastener is closed against interposed work parts, without resisting such axial movement.

4. In a tool for setting a bolt-type fastener comprising respective nut and screw elements having wrenching surfaces at the same end of the fastener, in combination: inner and outer wrenching members, one telescoped within the other; means for holdingthe outer member against rotation; and means for transmitting rotation to the inner member, said last means comprising a driving socket adapted to receive drive from a power source at its rear end and a shaft part telescoped in its forward end for limited rotative and axial movements therein, a helical camming groove in said socket, a drive projection extending radially from said shaft part into said groove, and a coil spring under compression between the rear end of said shaft part and said socket and normally projecting said shaft part to a forward limit of axial movement, said shaft part being coupled to said other wrenching member; said camming groove being pitched so as to resolve the drive torque into an axial pull on said shaft part balancing out the resistance to retraction of said shaft part developed in the transmission of torque from said socket to said shaft part, whereby said shaft part and said other wrenching member may retract in unison with the axial movement of said screw element into said nut element in response to rotation of the screw, without resistance to such axial movement.

5. A tool as defined in claim 4, wherein the said camming slot is pitched at an angle in the range between 10 and 30 as subtended from the drive axis, whereby the torque-energized pull on said shaft part is just sufiicient to overcome said resistance to retracting movement.

6. A tool as defined in claim 4, wherein said socket has a slot extending circumferentially from the forward end of said helical camming slot in cooperating with said projection to provide a self-indexing lost motion rotary connection between said socket and shaft part for facilitating the coupling of said other driving element to said screw. A

7. In a tool for setting a bolt-type fastener comprising respective nutand screw elements having wrenching surfaces at the same end of the fastener, in combinationf inner and outer wrenching members, one telescoped within the other; means for holding one of said members against rotation; and means for transmitting rotation to the other member, said last means comprising parts relatively shiftable axially and having limited rotative movement with respect to one another, one of said parts transmitting drive to said other member; means for transmitting rotary drive to the other part; and torquereactive means comprising a helical surface and a projection on the respective parts, said projection being engageable with said helical surface, said helical surface Ibeing pitched so as to resolve the drive torque into an axial thrust component substantially balancing out the resistance of the torque-loading coupling connection between said parts to the axial drawing of said parts together, whereby one of said parts may retract in unison with the axial movement of one of said fastener elements as the fastener is closed against interposed work parts, without resisting such axial movement.

8. A tool as defined in claim 7, including means springloading said parts for relative axial movement in which said projection assumes one limit position of movement along said helical surface.

9. A tool as defined in claim 8, wherein said wrenching members and said drive-transmitting means are arranged coaxially in an in-line assembly.

10. A tool as dened in claim 7, wherein said torquereactive means comprises an L-shaped slot having said helical surface in one portion thereof and having a circumferentially extending slot as the other portion thereof, said projection extending radially into said L-shaped slot and being movable in said circumferentially extending slot to provide a self-indexing lost motion rotary connection between said socket and shaft part for facilitating the coupling of said other driving element to said screw.

References Cited in the file of this patent UNITED STATES PATENTS 2,789,597 La Torre Apr. 23, 1957 2,820,382 Smith Jan. 2l, 1958 2,882,773 Wing Apr. 21, 1959 2,955,496 La Torre Oct. 11, 1960 3,016,774 Minobe Jan. 16, 1962 3,028,777 Essex Apr. 10, 1962 

1. IN A TOOL FOR SETTING A BOLT-TYPE FASTENER COMPRISING RESPECTIVE NUT AND SCREW ELEMENTS HAVING WRENCHING SURFACES AT THE SAME END OF THE FASTENER, IN COMBINATION: INNER AND OUTER WRENCHING MEMBERS, ONE TELESCOPED WITHIN THE OTHER; MEANS FOR HOLDING ONE OF SAID MEMBERS AGAINST ROTATION; AND MEANS FOR TRANSMITTING ROTATION TO THE OTHER MEMBER, SAID LAST MEANS COMPRISING PARTS RELATIVELY SHIFTABLE AXIALLY AND HAVING LIMITED ROTATIVE MOVEMENT WITH RESPECT TO ONE ANOTHER, ONE OF SAID PARTS TRANSMITTING DRIVE TO SAID OTHER MEMBER AND THE OTHER OF SAID PARTS RECEIVING DRIVE FROM A MOTOR, AND TORQUE-REACTIVE MEANS COMPRISING INTERENGAGING SURFACES OF SAID PARTS, AT LEAST ONE OF WHICH HAS AN ANGULAR INCLINATION WITH REFERENCE TO THE DRIVING AXIS OF THE TOOL, THEREBY COUPLING SAID PARTS IN A MANNER TO SUBSTANTIALLY ELIMINATE RESISTANCE TO RETRACTION OF SAID ONE PART WHEN TRANSMITTING TORQUE, WHEREBY SAID ONE PART MAY RETRACT IN UNISON WITH THE AXIAL MOVEMENT OF ONE OF SAID FASTENER ELEMENTS WITH RESPECT TO THE OTHER AS THE FASTENER IS CLOSED AGAINST PARTS TO BE FASTENED. 